I've noticed over the last few weeks more often that at idle my AFM voltage (R34 pink sticker) is hovering around 1.010-1.030, however on occasion, it will drop a little lower and hit 0.990-0.995v when it does, the idle goes super rich (like 11:1) and the car stumbles, the AAC opens up to bring the rpm up, then the rpm falls down and goes rich again.
Initially i thought this was related to the battery and alternator issue i had where the voltage would cycle 13.8 down to 13.4 (or lower sometimes) depending on the electrical load when the indicator was on. I have since replaced the battery and the alternator which has solved that issue.
Is this due to the AFM voltage being below a certain threshold (being 1.000v) ? or is it something i could tweak the VQ map a bit to keep it out of that particular cell ?
N15 Pulsar with SR20VE, 68C00 ECU, idle RPM 850-875.
My laptop is a bit sick right now so logging isn't possible, but i have an ECUtalk LCD + LC1 wideband to see whats going on to get the figures and data that i've posted. I have some CRC AFM Cleaner, is it worth removing and giving it a clean (was clean when installed ~18k ago)?
AFM <1.000v = very rich rough idle
Moderator: Matt
Re: AFM <1.000v = very rich rough idle
Sounds like it may be hitting a AFM limp value and thats why its going rich
Some of the other ECUs have a AFM low voltage parameter, may have to find it for this one for you
Some of the other ECUs have a AFM low voltage parameter, may have to find it for this one for you
Re: AFM <1.000v = very rich rough idle
my sr20 does exactly the same thing. I fixed it by raising the idle slightly. Not sure if there is a better way to get around it.
Re: AFM <1.000v = very rich rough idle
Hrm, i don't really want to run a higher idle though as just in that near range i get a lot of vibration with solid engine mounts, if i go lower on the idle, down to around 800rpm, there's no so much vibration oddly enough so if anything, i'd want to drop the idle from where it is now. hmmmm.
What baffles me is the car has been fine for the last 18,000 odd k's since i put the motor in, and that the issue has only recently come to light. Obviously things wear, pipes get clogged, idle valves get sticky etc etc over time, i guess the honey moon period is over !
I think i might re-check my battery and chassis earths as a precauction, although the AFM doesn't have a separate earth, i guess it can't hurt to check them.
What baffles me is the car has been fine for the last 18,000 odd k's since i put the motor in, and that the issue has only recently come to light. Obviously things wear, pipes get clogged, idle valves get sticky etc etc over time, i guess the honey moon period is over !
I think i might re-check my battery and chassis earths as a precauction, although the AFM doesn't have a separate earth, i guess it can't hurt to check them.
Re: AFM <1.000v = very rich rough idle
maybe the engine has started to loosen up a bit and needs less air to keep the idle ticking over? Another thing you could try is pull some timing out of the idle, it will have to compensate by opening the idle bypass and increase airflow slightly...
Re: AFM <1.000v = very rich rough idle
Yeh that's definintely possible, and having you say that, i just remembered 
this is the first time (although its been in for about 2,500km now) i've put Mobil 1 Synthetic 5W30 oil into the motor... I have been using Castrol Edge 5W30 previously.... Maybe the Mobil 1 is smoother and allowing things to move with less friction meaning less air needed to keep it ticking over... VERY interesting!
this is the first time (although its been in for about 2,500km now) i've put Mobil 1 Synthetic 5W30 oil into the motor... I have been using Castrol Edge 5W30 previously.... Maybe the Mobil 1 is smoother and allowing things to move with less friction meaning less air needed to keep it ticking over... VERY interesting!Re: AFM <1.000v = very rich rough idle
I realise you're really busy with more pressing & important things to check, but if this can be refreshed on your list to check & confirm that would be great.Matt wrote:Sounds like it may be hitting a AFM limp value and thats why its going rich
Some of the other ECUs have a AFM low voltage parameter, may have to find it for this one for you
Is there anything that can be done about this? Idle at 925rpm isn't too bad that i've had set for a while now (i replaced one of the solid mounts with an OEM one to reduce vibrations) but if there was a way around it, some tweak somewhere, that would be good.
Re: AFM <1.000v = very rich rough idle
Will have another look. There is a low AFM voltage setting which I've corrected and should be available for most SR20s next release
Re: AFM <1.000v = very rich rough idle
Just upgraded to the latest version (10.11 & 2.3.1) and either its not able to be adjusted for this Address file, or i can't find the setting, can you confirm if i should be able to lower this threshold value for the Type3 68C00.Matt wrote:Will have another look. There is a low AFM voltage setting which I've corrected and should be available for most SR20s next release
Cheers,
Simon.
Re: AFM <1.000v = very rich rough idle
Well i did a bit of digging myself and found the S13 address matches the Pulsar address so i added it to the Address file and it works. Problem is solved.
Re: AFM <1.000v = very rich rough idle
I've put this in the base SR20 file for next version (will show on all Type 3 SR20s) since was in S13, B13, N15 SR20 and S13 KA already